A hundred pollen and plant macrofossil records from the Iberian Peninsula, Southern France, the I... more A hundred pollen and plant macrofossil records from the Iberian Peninsula, Southern France, the Italian Peninsula, Greece and the Aegean, and the southwestern Black Sea area formed the basis for a review of the Quaternary distribution and extirpation of tree populations from Southern Europe. Following a discussion of the caveats/challenges about using pollen data, the Quaternary history of tree taxa has been reconstructed with attention to Taxodium/Glyptostrobus, Sciadopitys, Cathaya, Cedrus, Tsuga, Eucommia, Engelhardia, Carya, Pterocarya, Parrotia, Liquidambar, and Zelkova. The timing of extinction, distributed over the whole Quaternary, appears very diverse from one region to the other, in agreement with current biodiversity in Southern Europe. The geographical patterns of persistence/disappearance of taxa show unexpected trends and rule out a simple North to South and/or West to East trend in extirpations. In particular, it is possible to detect disjunct populations (Engelhardia), long-term persistence of taxa in restricted regions (Sciadopitys), distinct populations/species/genera in different geographical areas (Taxodium type). Some taxa that are still widespread in Europe have undergone extirpation in Medi-terranean areas in the lateglacial period and Holocene (Buxus, Carpinus betulus, Picea); they provide an indication of the modes of disappearance of tree populations that may be useful to evaluate correctly the vulnerability of modern fragmented plant populations. The demographic histories of tree taxa obtained by combined palaeobotanical and genetic studies is a most challenging field of research needed not only to assess species/population differentiation, but also to reach a better understanding of extinction processes , an essential task in the current global change scenario.
The Upper Arba de Biel constitutes a small valley in northeastern Spain where a detailed study of... more The Upper Arba de Biel constitutes a small valley in northeastern Spain where a detailed study of five archaeological sites (Pe~ na-14, Legunova/Rambla, Valcervera and Paco-Pons) has been performed, defining the recurrent prehistoric occupation from the Late Magdalenian until the Chalcolithic. The aim of this study focuses on exploring the main drivers of long-term human persistence on a particular humid shelter located in the Pre-Pyrenean area. The combination of a multiproxy dataset evidenced by the detailed synthesis of lithic tools and pottery, faunal remains, pollen and charcoal assemblages has been integrated with a GIS approach and a regional cultural and palaeoenvironmental contextualization. After an occupation gap that coincides with the second half of the Younger Dryas and the first Holocene millennia synchronous to other archaeological records found in NE Iberia, the Arba de Biel valley was recurrently visited by small hunteregatherer groups along the Mesolithic and by herders during the Neolithic. These people profited this territory, independently of environmental changes, because the easy access to a wide spectre of economic resources (flint nodules, diverse vegetation supplies, varied preys, etc.,) in a heterogeneous mosaic-type landscape. The valley main habitation spots (Pe~ na-14, Legunova/Rambla and Valcervera) could have been occupied at the same time by small groups that did not interfere each other. The use of the fifth rockshelter (Paco-Pons) seems to be related to the exploitation of copper mineral outcrops in the Neolithic and for metallurgical activities during the Chalcolithic. These last prehistoric visits to the valley reflect a notable shift in the human employment of the shelters: they cease to be living points to be used as funerary deposits.
Fluvial tufa located in the Queiles and Val river valleys (Moncayo Natural Park, Iberian Range, N... more Fluvial tufa located in the Queiles and Val river valleys (Moncayo Natural Park, Iberian Range, NE Iberia), are investigated following morphostratigraphic descriptions, radiocarbon dating and palynological and anthracological analyses. The studied tufa deposits have been chronologically framed within the Early-Mid Holocene (ca. 9500 to 4000 cal yr BP) in agreement with regional tufa build-up. Similarly, both climatic and palaeoenvironmental conditions reconstructed for this period fit with regional data from lacustrine records. The obtained pollen profiles and charcoal results show the existence of a local riparian woodland, where diverse mesophytes like deciduous Quercus, Corylus, Salix, Populus, Ulmus, Juglans and Hedera define the main vegetation features in the river valleys. Unexpectedly, both pollen and anthracological data also place Taxus baccata and Castanea sativa populations growing near the study area, and denoting, in the case of chestnut, its native and long-term presence in the Ibe-rian Range. Deciduous (Quercus faginea/pyrenaica type) and evergreen oaks (Quercus ilex/coccifera type) were the main spread regional forest which conformed the meso-Mediterranean vegetation belt of the Moncayo Range and borderlands, accompanied by many warm-loving shrubs like Olea, Phillyrea, Rhamnus and Pistacia, pointing out the optimal thermic period of the Holocene. Pine (Pinus nigra/sylvestris type) and montane broadleaved communities (Betula, Fagus) were usually confined to high-altitude elevations, but anthracological record also address local presence. The combination of pollen and charcoal analyses together with the dating tufa of build-ups, represent an essential tool to complete the regional palaeoclimatic and palaeohydrological reconstructions as well as to address precisely the past distribution of unusual taxa.
Understanding long-term fire ecology is essential for current day interpretation of ecosystem fir... more Understanding long-term fire ecology is essential for current day interpretation of ecosystem fire responses. However palaeoecology of fire is still poorly understood, especially at high-altitude mountain environments, despite the fact that these are fire-sensitive ecosystems and their resilience might be affected by changing fire regimes. We reconstruct wildfire occurrence since the Lateglacial (14.7 cal ka BP) to the Mid-Holocene (6 cal ka BP) and investigate the climate–fuel–fire relationships in a sedimentary sequence located at the treeline in the Central Spanish Pyrenees. Pollen, macro-and micro-charcoal were analysed for the identification of fire events (FE) in order to detect vegetation post-fire response and to define biomass–fire interactions. mean fire intervals (mfi) reduced since the Lateglacial, peaking at 9–7.7 cal ka BP while from 7.7 to 6 cal ka BP no fire is recorded. We hypothesise that Early Holocene maximum summer insolation, as climate forcing, and mesophyte forest expansion , as a fuel-creating factor, were responsible for accelerating fire occurrence in the Central Pyrenees treeline. We also found that fire had long-lasting negative effects on most of the treeline plant communities and that forest contraction from 7.7 cal ka BP is likely linked to the ecosystem's threshold response to high fire frequencies.
In this contribution we compile and summarize the available paleo-environmental lacustrine data f... more In this contribution we compile and summarize the available paleo-environmental lacustrine data for the last 20,000 years from the southern Central Pyrenees (from west to east: El Portalet, Tramacastilla, Basa de la Mora, Estanya, Redon, Montcortès and Marcelino lakes) and present a new sequence from mid altitude (Holocene record of Lake Estanya). Multiproxy analyses of lake records have identified large vegetation and hydrological changes during last glacial, deglaciation and the Holocene periods at millennial, centennial and even decadal scales and documented their timing, intensity and varied nature. The review indicates that landscape dynamics in the Pyrenees have been greatly controlled by both long term and abrupt climate changes and, since the Middle Holocene, and particularly since Medieval times, by human activities as new transforming agent. Although high internal variability characterized every site, common temporal trends are evidenced, as well as a suggestive western–eastern gradient superimposed to the expected altitudinal one (highlands versus lowlands). Thus, the long-term Central Pyrenees environmental history presents a relatively high degree of internal coherence across space and provides some past scenarios of landscape-climate interactions to evaluate the expected impacts of current and future Global Change.
The sedimentological, geochemical and palynological analyses performed in the Conquezuela palaeol... more The sedimentological, geochemical and palynological analyses performed in the Conquezuela palaeolake (41°11′ N; 2°33′W; 1124 m a.s.l.) provide a detailed, multiproxy palaeoenvironmental reconstruction in one of the key areas of inner Iberian Neolithic colonization. Combined with archaeobotanical and archaeological data from well-dated settlements along the Conquezuela–Ambrona Valley we investigate how environmental conditions may affect both socioeconomic adaptations and livelihood strategies of prehistoric communities. The first evi-dences of early Neolithic occupation in the valley ca. 7250–6450 cal yr BP (5300–4500 BC) coincided with the onset of a period (7540–6200 cal yr BP, 5590–4250 BC) with higher water availability and warmer climate as alluvial environments were substituted by carbonate-wetland environments in the basin. The Conquezuela record supports an early Neolithic colonization of the inner regions of Iberia favored by warmer and humid climate features and with preferential settlement patterns associated to lakes. The maximum human occupation of the valley occurred during the mid–late Neolithic and Chalcolithic (6200–3200 cal yr BP, 4250–1250 BC) as evidenced by the high number of archaeological sites. Although a number of hydrological oscillations have been detected during this period, the intense landscape transformation at basin-scale, leading to a deforested landscape, was largely a consequence of widespread farming and pastoral practices. Socioeconomic activities during Bronze, Iron and Roman times modified this inherited landscape, but the second largest ecosystem transformation only occurred during Mediaeval times when a new agrarian landscape developed with the expansion of stockbreeding transhumance. The current vegetation cover characterized by patches of holm and marcescent oaks and fields reflects an intense human management combining both extensive herding with agrarian activities in order to transform the previous forested landscape into a dehesa-like system.
Palynological, sedimentological and geochemical analyses performed on the Villarquemado paleolake... more Palynological, sedimentological and geochemical analyses performed on the Villarquemado paleolake sequence
(987 m a.s.l, 40°30′N; 1°18′W) reveal the vegetation dynamics and climate variability in continental Iberia over
the last 13,500 cal yr BP. The Lateglacial and early Holocene periods are characterized by arid conditions with a
stable landscape dominated by pinewoods and steppe until ca. 7780 cal yr BP, despite sedimentological evidence
for large paleohydrological fluctuations in the paleolake. The most humid phase occurred between ca. 7780 and
5000 cal yr BP and was characterized by the maximum spread of mesophytes (e.g., Betula, Corylus, Quercus
faginea type), the expansion of a mixed Mediterranean oak woodlandwith evergreen Quercus as dominant forest
communities and more frequent higher lake level periods. The return of a dense pinewood synchronouswith the
depletion of mesophytes characterizes the mid-late Holocene transition (ca. 5000 cal yr BP) most likely as a consequence
of an increasing aridity that coincides with the reappearance of a shallow, carbonate wetland environment.
The paleohydrological and vegetation evolution shows similarities with other continental Mediterranean
areas of Iberia and demonstrates a marked resilience of terrestrial vegetation and gradual responses to millennialscale
climate fluctuations. Human impact is negligible until the Ibero-Roman period (ca. 2500 cal yr BP) when a
major deforestation occurred in the nearby pine forest. The last 1500 years are characterized by increasing landscape
management, mainly associated with grazing practices shaping the current landscape.
A hundred pollen and plant macrofossil records from the Iberian Peninsula, Southern France, the I... more A hundred pollen and plant macrofossil records from the Iberian Peninsula, Southern France, the Italian Peninsula, Greece and the Aegean, and the southwestern Black Sea area formed the basis for a review of the Quaternary distribution and extirpation of tree populations from Southern Europe. Following a discussion of the caveats/challenges about using pollen data, the Quaternary history of tree taxa has been reconstructed with attention to Taxodium/Glyptostrobus, Sciadopitys, Cathaya, Cedrus, Tsuga, Eucommia, Engelhardia, Carya, Pterocarya, Parrotia, Liquidambar, and Zelkova. The timing of extinction, distributed over the whole Quaternary, appears very diverse from one region to the other, in agreement with current biodiversity in Southern Europe. The geographical patterns of persistence/disappearance of taxa show unexpected trends and rule out a simple North to South and/or West to East trend in extirpations. In particular, it is possible to detect disjunct populations (Engelhardia), long-term persistence of taxa in restricted regions (Sciadopitys), distinct populations/species/genera in different geographical areas (Taxodium type). Some taxa that are still widespread in Europe have undergone extirpation in Medi-terranean areas in the lateglacial period and Holocene (Buxus, Carpinus betulus, Picea); they provide an indication of the modes of disappearance of tree populations that may be useful to evaluate correctly the vulnerability of modern fragmented plant populations. The demographic histories of tree taxa obtained by combined palaeobotanical and genetic studies is a most challenging field of research needed not only to assess species/population differentiation, but also to reach a better understanding of extinction processes , an essential task in the current global change scenario.
The Upper Arba de Biel constitutes a small valley in northeastern Spain where a detailed study of... more The Upper Arba de Biel constitutes a small valley in northeastern Spain where a detailed study of five archaeological sites (Pe~ na-14, Legunova/Rambla, Valcervera and Paco-Pons) has been performed, defining the recurrent prehistoric occupation from the Late Magdalenian until the Chalcolithic. The aim of this study focuses on exploring the main drivers of long-term human persistence on a particular humid shelter located in the Pre-Pyrenean area. The combination of a multiproxy dataset evidenced by the detailed synthesis of lithic tools and pottery, faunal remains, pollen and charcoal assemblages has been integrated with a GIS approach and a regional cultural and palaeoenvironmental contextualization. After an occupation gap that coincides with the second half of the Younger Dryas and the first Holocene millennia synchronous to other archaeological records found in NE Iberia, the Arba de Biel valley was recurrently visited by small hunteregatherer groups along the Mesolithic and by herders during the Neolithic. These people profited this territory, independently of environmental changes, because the easy access to a wide spectre of economic resources (flint nodules, diverse vegetation supplies, varied preys, etc.,) in a heterogeneous mosaic-type landscape. The valley main habitation spots (Pe~ na-14, Legunova/Rambla and Valcervera) could have been occupied at the same time by small groups that did not interfere each other. The use of the fifth rockshelter (Paco-Pons) seems to be related to the exploitation of copper mineral outcrops in the Neolithic and for metallurgical activities during the Chalcolithic. These last prehistoric visits to the valley reflect a notable shift in the human employment of the shelters: they cease to be living points to be used as funerary deposits.
Fluvial tufa located in the Queiles and Val river valleys (Moncayo Natural Park, Iberian Range, N... more Fluvial tufa located in the Queiles and Val river valleys (Moncayo Natural Park, Iberian Range, NE Iberia), are investigated following morphostratigraphic descriptions, radiocarbon dating and palynological and anthracological analyses. The studied tufa deposits have been chronologically framed within the Early-Mid Holocene (ca. 9500 to 4000 cal yr BP) in agreement with regional tufa build-up. Similarly, both climatic and palaeoenvironmental conditions reconstructed for this period fit with regional data from lacustrine records. The obtained pollen profiles and charcoal results show the existence of a local riparian woodland, where diverse mesophytes like deciduous Quercus, Corylus, Salix, Populus, Ulmus, Juglans and Hedera define the main vegetation features in the river valleys. Unexpectedly, both pollen and anthracological data also place Taxus baccata and Castanea sativa populations growing near the study area, and denoting, in the case of chestnut, its native and long-term presence in the Ibe-rian Range. Deciduous (Quercus faginea/pyrenaica type) and evergreen oaks (Quercus ilex/coccifera type) were the main spread regional forest which conformed the meso-Mediterranean vegetation belt of the Moncayo Range and borderlands, accompanied by many warm-loving shrubs like Olea, Phillyrea, Rhamnus and Pistacia, pointing out the optimal thermic period of the Holocene. Pine (Pinus nigra/sylvestris type) and montane broadleaved communities (Betula, Fagus) were usually confined to high-altitude elevations, but anthracological record also address local presence. The combination of pollen and charcoal analyses together with the dating tufa of build-ups, represent an essential tool to complete the regional palaeoclimatic and palaeohydrological reconstructions as well as to address precisely the past distribution of unusual taxa.
Understanding long-term fire ecology is essential for current day interpretation of ecosystem fir... more Understanding long-term fire ecology is essential for current day interpretation of ecosystem fire responses. However palaeoecology of fire is still poorly understood, especially at high-altitude mountain environments, despite the fact that these are fire-sensitive ecosystems and their resilience might be affected by changing fire regimes. We reconstruct wildfire occurrence since the Lateglacial (14.7 cal ka BP) to the Mid-Holocene (6 cal ka BP) and investigate the climate–fuel–fire relationships in a sedimentary sequence located at the treeline in the Central Spanish Pyrenees. Pollen, macro-and micro-charcoal were analysed for the identification of fire events (FE) in order to detect vegetation post-fire response and to define biomass–fire interactions. mean fire intervals (mfi) reduced since the Lateglacial, peaking at 9–7.7 cal ka BP while from 7.7 to 6 cal ka BP no fire is recorded. We hypothesise that Early Holocene maximum summer insolation, as climate forcing, and mesophyte forest expansion , as a fuel-creating factor, were responsible for accelerating fire occurrence in the Central Pyrenees treeline. We also found that fire had long-lasting negative effects on most of the treeline plant communities and that forest contraction from 7.7 cal ka BP is likely linked to the ecosystem's threshold response to high fire frequencies.
In this contribution we compile and summarize the available paleo-environmental lacustrine data f... more In this contribution we compile and summarize the available paleo-environmental lacustrine data for the last 20,000 years from the southern Central Pyrenees (from west to east: El Portalet, Tramacastilla, Basa de la Mora, Estanya, Redon, Montcortès and Marcelino lakes) and present a new sequence from mid altitude (Holocene record of Lake Estanya). Multiproxy analyses of lake records have identified large vegetation and hydrological changes during last glacial, deglaciation and the Holocene periods at millennial, centennial and even decadal scales and documented their timing, intensity and varied nature. The review indicates that landscape dynamics in the Pyrenees have been greatly controlled by both long term and abrupt climate changes and, since the Middle Holocene, and particularly since Medieval times, by human activities as new transforming agent. Although high internal variability characterized every site, common temporal trends are evidenced, as well as a suggestive western–eastern gradient superimposed to the expected altitudinal one (highlands versus lowlands). Thus, the long-term Central Pyrenees environmental history presents a relatively high degree of internal coherence across space and provides some past scenarios of landscape-climate interactions to evaluate the expected impacts of current and future Global Change.
The sedimentological, geochemical and palynological analyses performed in the Conquezuela palaeol... more The sedimentological, geochemical and palynological analyses performed in the Conquezuela palaeolake (41°11′ N; 2°33′W; 1124 m a.s.l.) provide a detailed, multiproxy palaeoenvironmental reconstruction in one of the key areas of inner Iberian Neolithic colonization. Combined with archaeobotanical and archaeological data from well-dated settlements along the Conquezuela–Ambrona Valley we investigate how environmental conditions may affect both socioeconomic adaptations and livelihood strategies of prehistoric communities. The first evi-dences of early Neolithic occupation in the valley ca. 7250–6450 cal yr BP (5300–4500 BC) coincided with the onset of a period (7540–6200 cal yr BP, 5590–4250 BC) with higher water availability and warmer climate as alluvial environments were substituted by carbonate-wetland environments in the basin. The Conquezuela record supports an early Neolithic colonization of the inner regions of Iberia favored by warmer and humid climate features and with preferential settlement patterns associated to lakes. The maximum human occupation of the valley occurred during the mid–late Neolithic and Chalcolithic (6200–3200 cal yr BP, 4250–1250 BC) as evidenced by the high number of archaeological sites. Although a number of hydrological oscillations have been detected during this period, the intense landscape transformation at basin-scale, leading to a deforested landscape, was largely a consequence of widespread farming and pastoral practices. Socioeconomic activities during Bronze, Iron and Roman times modified this inherited landscape, but the second largest ecosystem transformation only occurred during Mediaeval times when a new agrarian landscape developed with the expansion of stockbreeding transhumance. The current vegetation cover characterized by patches of holm and marcescent oaks and fields reflects an intense human management combining both extensive herding with agrarian activities in order to transform the previous forested landscape into a dehesa-like system.
Palynological, sedimentological and geochemical analyses performed on the Villarquemado paleolake... more Palynological, sedimentological and geochemical analyses performed on the Villarquemado paleolake sequence
(987 m a.s.l, 40°30′N; 1°18′W) reveal the vegetation dynamics and climate variability in continental Iberia over
the last 13,500 cal yr BP. The Lateglacial and early Holocene periods are characterized by arid conditions with a
stable landscape dominated by pinewoods and steppe until ca. 7780 cal yr BP, despite sedimentological evidence
for large paleohydrological fluctuations in the paleolake. The most humid phase occurred between ca. 7780 and
5000 cal yr BP and was characterized by the maximum spread of mesophytes (e.g., Betula, Corylus, Quercus
faginea type), the expansion of a mixed Mediterranean oak woodlandwith evergreen Quercus as dominant forest
communities and more frequent higher lake level periods. The return of a dense pinewood synchronouswith the
depletion of mesophytes characterizes the mid-late Holocene transition (ca. 5000 cal yr BP) most likely as a consequence
of an increasing aridity that coincides with the reappearance of a shallow, carbonate wetland environment.
The paleohydrological and vegetation evolution shows similarities with other continental Mediterranean
areas of Iberia and demonstrates a marked resilience of terrestrial vegetation and gradual responses to millennialscale
climate fluctuations. Human impact is negligible until the Ibero-Roman period (ca. 2500 cal yr BP) when a
major deforestation occurred in the nearby pine forest. The last 1500 years are characterized by increasing landscape
management, mainly associated with grazing practices shaping the current landscape.
Uploads
Papers by Josu Aranbarri
(987 m a.s.l, 40°30′N; 1°18′W) reveal the vegetation dynamics and climate variability in continental Iberia over
the last 13,500 cal yr BP. The Lateglacial and early Holocene periods are characterized by arid conditions with a
stable landscape dominated by pinewoods and steppe until ca. 7780 cal yr BP, despite sedimentological evidence
for large paleohydrological fluctuations in the paleolake. The most humid phase occurred between ca. 7780 and
5000 cal yr BP and was characterized by the maximum spread of mesophytes (e.g., Betula, Corylus, Quercus
faginea type), the expansion of a mixed Mediterranean oak woodlandwith evergreen Quercus as dominant forest
communities and more frequent higher lake level periods. The return of a dense pinewood synchronouswith the
depletion of mesophytes characterizes the mid-late Holocene transition (ca. 5000 cal yr BP) most likely as a consequence
of an increasing aridity that coincides with the reappearance of a shallow, carbonate wetland environment.
The paleohydrological and vegetation evolution shows similarities with other continental Mediterranean
areas of Iberia and demonstrates a marked resilience of terrestrial vegetation and gradual responses to millennialscale
climate fluctuations. Human impact is negligible until the Ibero-Roman period (ca. 2500 cal yr BP) when a
major deforestation occurred in the nearby pine forest. The last 1500 years are characterized by increasing landscape
management, mainly associated with grazing practices shaping the current landscape.
(987 m a.s.l, 40°30′N; 1°18′W) reveal the vegetation dynamics and climate variability in continental Iberia over
the last 13,500 cal yr BP. The Lateglacial and early Holocene periods are characterized by arid conditions with a
stable landscape dominated by pinewoods and steppe until ca. 7780 cal yr BP, despite sedimentological evidence
for large paleohydrological fluctuations in the paleolake. The most humid phase occurred between ca. 7780 and
5000 cal yr BP and was characterized by the maximum spread of mesophytes (e.g., Betula, Corylus, Quercus
faginea type), the expansion of a mixed Mediterranean oak woodlandwith evergreen Quercus as dominant forest
communities and more frequent higher lake level periods. The return of a dense pinewood synchronouswith the
depletion of mesophytes characterizes the mid-late Holocene transition (ca. 5000 cal yr BP) most likely as a consequence
of an increasing aridity that coincides with the reappearance of a shallow, carbonate wetland environment.
The paleohydrological and vegetation evolution shows similarities with other continental Mediterranean
areas of Iberia and demonstrates a marked resilience of terrestrial vegetation and gradual responses to millennialscale
climate fluctuations. Human impact is negligible until the Ibero-Roman period (ca. 2500 cal yr BP) when a
major deforestation occurred in the nearby pine forest. The last 1500 years are characterized by increasing landscape
management, mainly associated with grazing practices shaping the current landscape.